I'll never get the complaints on the GCD - I mean sure it's slower than other games but why does everything have to be a comparison? If you gotta compare everything, use the time between abilities to appreciate everything else this game does right over the MMO you probably recently quit. Take a breath. I'm not sure when this mentality of "combat has to match the speed of my heart rate after I just snorted a gram of Colombian yeyo and chugged 3 pots of coffee" but it's ok to just take your time, and enjoy the ride.
I'll be honest too, right now most jobs on this game feel like they have more off-GCD cooldown abilities than the average WoW class does these days anyway. That extra time has a purpose too for some jobs, ie the ones with positionals. If I had to do positionals with a GCD akin to WoW....christ i'd have some insane case of carpal tunnel by now. That and my character would look like some spastic retard bouncing all over the place during a boss fight.
Just go into this game leveling up a new job without the expectations of a quick leveling up experience boosted all to hell and back like most MMO's do these days, and think of it as simply a right of passage until things get better, ala EQ, and you'll be fine.
Does it suck for a brand new person? Yes, if you have the attention span of a goldfish. There's so much beauty to the world that you should be appreciating instead of just focusing on a damn GCD timer.
Does it get better once you get closer to max level? Yes, but it's never gonna be as fast as (whatever game).
Is it worth it in the long run? Yes, a thousand times yes. If you can't appreciate the intricacies of how this game blends old content with new to keep things flowing for both new and old players, you're really selling this game short.
I've said it before, and though there's always gonna be disagreement on this point - I find the average quality of player in FFXIV hands down better than the average quality player you'd find in WoW. Maybe it's the slow GCD that makes weaker players quit early, maybe it's the rough opening level experience; who knows.